This invention relates to a catalyst used in production of methacrylic acid by vapor phase catalytic oxidation of methacrolein and a process for production of methacrylic acid.
Hitherto, there have been proposed processes for production of unsaturated carboxylic acids by vapor phase catalytic oxidation of unsaturated aldehydes in many patents. Most of them have aimed at production of acrylic acid from acrolein and when catalysts proposed in these patents are used for production of methacrylic acid, selectivity is small because of considerable side reactions and besides life of the catalyst is so short that the catalyst is not able to practically use.
On the other hand, a number of catalysts have been proposed for production of methacrylic acid from methacrolein. However, they suffer from the problems such as insufficient reaction results, a large deterioration of catalyst activity with time, too high reaction temperature, etc. Thus, further improvement in catalyst has been demanded for commercial use.